1. might fly in some purely-functional Lisp, but most (all?) real-world Lisps can have side effects in macro expansion. And by "side effects", I don't mean altering some global variable or adding a function to the symbol table - Lisp macros have access to the full language runtime, so a macroexpansion may just as well send some HTTP requests or hit a database.

Ironically, the author of the article was correct in their view that he initially described as wrong. Macros are just functions, typically taking code and outputting code. They just didn't understand the evaluation rules surrounding macro invocation.